Power supply to the Servo Driver

tran9774 commented 3 years ago

Hi guys.

I'm following this build but I didn't purchase a rc controller because I wanted to use my xbox controller for it. How do you supply power to the PCA9685 to move the Servo?

Greetings from Germany.

akwong922 commented 3 years ago

I did something similar with a PS3 controller. The PCA9685 powers up when connected to the ESC when powered on and i can control the throttle and the steering from it. Not sure if this will cause any problems in the long run though.

tran9774 commented 3 years ago

How did you setup the ESC in that case. Because i don't have a radio transmitter the ESC keeps beeping. I can control the steering with the Adafruit servo kit library in Python though.

wackerl91 commented 3 years ago

I have pretty much the same setup. Here is what I did:

Jetson Nano is connected to the PCA9685 using the usual 4-wires connection (powers on with the Jetson)
Steering servo is connected with all three pins on the PWM headers
ESC is connected to the PCA9685 using only the PWM signal on the PWM header (not GND/V+, so the Jeston only sends the PWM signal via the PCA9685 board)
GND/V+ to PCA9685 is supplied from ESC using the green/blue power terminal connector (opposite of the PWM header on the PCA9685 board; not sure if this is strictly necessary as I haven't tried disconnecting those cables)

To my understanding (not an electrics guy ...), this way the servos draw power via the ESC from the car battery instead of from the Jetson - on Adafruit there's a warning that excessive current may cause resets and/or damage when an Arduino provides the power, so I figured the same may be the case for the Jetson.

Regarding the ESC, it beeps as long as no control input has been received. I set both steering servo and motor to 0 when launching my script before switching on the ESC.

Feel free to shoot me a mail if some photos would help you with wiring everything up.

Cheers, and have fun with your Jetracer! :)

dbanshee commented 2 years ago

Hi guys, building a similar configuration too, I've noticed (at least in my setup) that Voltage on PWM cables from ESC are higher than reasonable 5V. I read 5.9V and this is propagated to PCA9685 and Jetson (really an rpi, but it is not rellevant). So I think this could be dangerous.

I'm not using a battery. I'm using an ATX PSU instead, converting from 12V to 7V with DC-DC stepper down. Can you check the theorically 5V ESC line with full battery?

I've created a new issue with more details before you are interested.

Grettings from Spain.

NVIDIA-AI-IOT / jetracer

Power supply to the Servo Driver #106